1. Field of the Invention
The present invention relates to an image reading apparatus, such as an image scanner or the like, having a light irradiating means for irradiating, for example, linear light to a subject, such as an object having images to be read, an image forming means, such as a linear lens array or the like, for making the light from the subject incident on an image plane so as to form images as erected images, and a photoelectric conversion means for converting the incident light of the erected images into image signals; and an optical module constituted by unitizing the light irradiating means, the image forming means and the photoelectric conversion means.
2. Description of the Related Art
In an image reading apparatus, such as a copy machine or a peripheral device and a multifunction machine using the same, an image scanner, a facsimile or the like, in the related art, copying, printing or the like has been performed by making a reading unit having a contact image sensor (CIS) module or the like scan an object placed and fixed on a cover glass surface (generally, a soda lime glass with a thickness of 2.9 mm), transmitting image information of letters, photos or the like on the object planes (reflected light from the object planes) at each scanning position to a rod lens array, making the rod lens array form erected images of unity magnification on a charge-coupled device (CCD) linear sensor, a complementary metal oxide semiconductor (CMOS) linear sensor or the like, and then synthesizing and processing image signals obtained from the sensor.
On the other hand, like an information processing apparatus shown in Japanese Patent No. 3507284 to be described below or the like, an apparatus is also used that automatically transports an object plane and reads letters, photos or the like on the object plane beyond the surface of the cover glass (with a thickness of about 1 mm). In addition, there is an apparatus provided with reading apparatuses at both sides to read the front and rear planes of an object so as to perform reading of both planes at the same time.
In any case, the light to be irradiated on an object plane is emitted from a plurality of LEDs (light emission diodes with emission colors of R, G, B or the like) positioned at the end surface of a light guide body, but is uniformly dispersed and diffused in the identical or perpendicular direction to the scanning direction of a scanner or the like by the light guide body made of plastic, such as an acrylic resin or the like, and is irradiated on an object plane. The irradiated light is reflected from the object plane, and the reflected light passes through the rod lens array or the like, and is guided to the CCD or CMOS sensor disposed in a linear format, and is read as image signals of the object. In this case, a widely used rod lens array is a SELFOC Lens, manufactured by Nippon Sheet Glass Co., Ltd.